Assembly for food product and method for heating said assembly

ABSTRACT

The invention relates to a pack for a food product comprising
     a tray  1  with a lip  4,  a side wall  3  and a bottom  2,     a film  6  sealed all around the periphery of said tray, partly over the lip and over the top of the side wall, directly adjacent to said lip, and   a food composition  5  contained in said tray,   

     the film coming substantially into contact with the food composition.

The present invention relates to a pack for a food product and a heating and/or cooking method for said pack.

Film-covered trays containing food products which are heated up in microwave ovens are already known. With these trays, as a food product packaged inside this type of packaging is regenerated, the water contained in the food evaporates under the effect of the energy supplied by the microwaves. The increase in pressure inside the packaging caused by the formation of steam causes the upper film to rise. When a threshold pressure inside the packaging is reached, the welded edges will yield at a point which we will call the rupture point, in order to release this excess steam. This phenomenon is known as “self-venting”. In the case of products with a high water content such as meals in sauce, it may happen that during regeneration the sauce, brought to boiling point, rises up as far as the rupture point, leaks out of the packaging and dribbles down over the plate of the microwave oven. This phenomenon is often observed with sauces with a high content of foaming agents (milk proteins, mushroom extracts) and with emulsion sauces containing crème fraîche, margarine, butter, oil or any other fat dispersed in an aqueous phase. The higher the power of the microwaves used for regeneration, the worse this phenomenon will be.

The aim of the present invention is to provide the consumer with a pack for microwave-regeneratable food products in which there is no risk of the food product overflowing during heating in said microwave oven.

The present invention relates to a pack for a food product comprising

-   a tray with a lip, a side wall and a bottom, -   a film sealed all around the periphery of said tray, partly over the     lip and over the top of the side wall, directly adjacent to said     lip, and -   a food composition contained in said tray,

the film coming substantially into contact with the food composition.

The pack according to the invention differs from the prior art in that the tray is made of a material such that the lip of said tray deforms under the effect of the microwaves, thus preventing any leakage of product out of the tray. Specifically, during regeneration, the film rises under the effect of the pressure and exerts a force on the welded edges, causing the lip of the tray to tilt vertically. Hence, when the threshold pressure is reached, the rupture point will be oriented vertically, thus forming a chimney allowing the steam to escape. Therefore, since the rupture point is oriented vertically, the boiling sauce does not flow over the top of the lip and will thus not leak out of the packaging.

As mentioned above, to ensure that the lip of the tray does indeed rise, it must be made of a material allowing said lip to rise easily. Preferably, the material from which the tray is made is a multilayer composite comprising the following layers, alone or in combination:

-   Ionomer resin, -   Ethylene methacrylic acid (EMA) copolymer, -   Low density polyethylene (PE), -   Polybutylene, -   Adhesive resin, -   Polypropylene, -   Ethylene vinyl acetate (EVA) copolymer and -   Ethylene vinyl alcohol (EVOH) copolymer.

The thickness of the wall of the tray is between 400 and 700 μm. Preferably, the thickness of the wall of the tray is between 400 and 500 μm.

It is also important in the pack according to the invention that the side wall of the tray make an angle of between 1 and 5° with the vertical. The steep slope makes it possible to limit access by the boiling sauce to the rupture point. This steep slope also considerably reduces the burnt appearance of the sauce observed with trays having an angle of between 5 and 10°. With such trays, a skin of sauce forms on the walls of the tray, which dries out during regeneration and which, owing to the combined effect of heat, evaporation and the presence of reducing sugars and amino acids, is the target of Maillard reactions causing the walls of the tray to appear burnt.

The material from which the film is made is a multilayer composite comprising the following layers, alone or in combination:

-   Ionomer resin, -   Ethylene vinyl alcohol (EVOH) copolymer, -   High density polyethylene, -   Adhesive resin, -   EVA.

The thickness of the film is between 100 and 150 μm.

The food composition contained in the tray is a refrigerated composition or frozen composition. It is normally regenerated by microwaving but may also be regenerated using a water bath. The food composition is chosen from the group of compositions comprising sauces, pasta, rice, potatoes, vegetables, meat, fish and any other food product. It may be a complete meal or a side dish. The composition in a sauce is a composition comprising, as well as the sauce, pasta, rice, potatoes, vegetables, fish, meat and any other food product.

The food composition occupies a volume of between 30 and 97% of the volume of the tray. Preferably, the food composition occupies between 60 and 97% of the volume of the tray. For products containing sauces with a high content of foaming agents and fat, the volume occupied by the product must not exceed 60% of the total volume of the tray. For products with a lot of sauce which is not an emulsion and has a low foaming agent content, the volume of the product may occupy up to 97% of the volume of the tray.

The tilting of the welded edges during regeneration of the tray by microwaves is helped by giving the tray a rounded shape along its length. By virtue of this shape, the tilting of the welded edges is maximized midway along the curved walls of the tray and the rupture point will form at this spot.

The method for manufacturing the pack according to the invention is essentially as follows:

-   a sheet of plastic is thermoformed to produce the tray, -   the food product is dispensed into said tray, -   a vacuum is created and, at the same time, the film is sealed on top     of the tray.

The product is packaged under a vacuum of around 10 to 300 mbar.

When the pack according to the invention is manufactured, it is stored either refrigerated or frozen.

The advantages of the pack according to the invention are immediately obvious when used by the consumer. The present invention relates to a method of heating and/or cooking a pack as described above, in which

-   the pack is placed in a system of heating by microwaves, -   microwave heating is commenced, -   heating is continued until the film deforms under the effect of the     rise in pressure inside the tray and partially detaches over a     section of the periphery of said tray, and -   heating or cooking is continued.

As already stated above, during heating or cooking, the deformation of the film allows the lip of the tray to rise.

The rupture point appears normally after 2 to 4 minutes. The heating time is between 30 seconds and 10 minutes. Preferably, the heating time is around 6 minutes. Heating takes less time, depending also on the size of the tray, and for cooking the time taken is longer.

The remainder of the description is provided with reference to the drawings, in which:

FIG. 1 is a perspective view of the tray used,

FIG. 2 is a longitudinal section through the pack according to the invention,

FIG. 3 is a top view of the pack according to the invention, and

FIG. 4 is a view of the pack at the moment the film opens.

The tray 1 comprises a bottom 2, a side wall 3 and a lip 4. This tray is made of a PP-EVOH-EVA multilayer having a thickness of 500 μm. It has a capacity of 330 or 430 ml and is designed to contain a frozen meal weighing 150 to 400 g.

FIG. 2 shows the tray 1 containing a ready meal 5 and a film 6 sealing off the top of the tray.

FIG. 3 shows that the tray 1 comprises a wall rounded outwards along its length and it is substantially midway along this length at 7 that the film becomes detached and creates a rupture point for steam to escape. The tray may also be rounded along its width, in which case it is rounded inwards.

Lastly, FIG. 4 clearly shows that, during heating in a microwave oven or any other heating device, the film 6 rises under the effect of the rise in pressure, causing the lip 4 of the tray to rise until the rupture point is reached. The lip rises around the whole periphery of the tray and, because it is raised, even at the time of rupture nothing can flow onto the plate of the microwave oven.

EXAMPLE

Take a pack according to the invention with a capacity of 330 ml containing 100 g of fish and 100 g of sauce. The pack is frozen. It is placed in a microwave oven with a power of 1000 W and heating is commenced. After 6 minutes, the meal has been heated and the film has opened over a distance of 20 mm. The lip of the tray has risen around the whole periphery and nothing has flowed onto the plate of the microwave oven. 

1. Pack for a food product comprising a tray with a lip, a side wall and a bottom, a film sealed all around a periphery of the tray, partly over the lip and over the top of the side wall, directly adjacent to the lip, a food composition contained in the tray, and the film coming substantially into contact with the food composition.
 2. Pack according to claim 1, wherein the side wall of the tray makes an angle of between 1 and 5° Ma vertical plane of the tray.
 3. Pack according to claim 1, wherein the tray is constructed from a multilayer composite.
 4. Pack according to claim 3, wherein the thickness of the side wall of the tray is between 400 and 700 μm.
 5. Pack according to claim 1, wherein the material from which the film is made is a Surylin-EVOH-Surylin multilayer composite.
 6. Pack according to claim 5, wherein the thickness of the film is between 100 and 150 μm.
 7. Pack according to claim 1, wherein the food composition is selected from the group consisting of a refrigerated composition and a frozen composition.
 8. Pack according to claim 7, wherein the food composition is chosen from the group of compositions consisting of sauces, pasta, rice, potatoes, vegetables, meat, and fish.
 9. Pack according to claim 8, wherein the composition is in a sauce.
 10. Pack according to claim 1, wherein the wall of the tray is rounded along a length.
 11. Pack according to claim 1, wherein the food composition occupies a volume of between 30 and 97% of a volume of the tray.
 12. Pack according to claim 1, wherein the food composition is packaged under a vacuum of between 10 and 300 mbar.
 13. A method of heating a pack comprising: a tray with a lip, a side wall and a bottom, a film sealed all around a periphery of the tray, partly over the lip and over the top of the side wall, directly adjacent to the lip, a food composition contained in the tray, the film coming substantially into contact with the food composition comprising the steps of placing the pack in a microwave device, using microwaves to heat the pack, heating is continued until the film deforms under the effect of the rise in pressure inside the tray and partially detaches over a section of the periphery of the tray, and heating is continued.
 14. Method according to claim 13, wherein during heating, the deformation of the film allows the lip of the tray to rise.
 15. Method according to claim 13, wherein the heating time is between 30 seconds and 10 minutes. 